LED retrofit lamps or their light sources are typically operated with a safety extra-low voltage (SELV). For this purpose the LED retrofit lamp includes a driver for operating the LED(s) which includes a voltage regulator, typically a transformer, for converting a mains voltage, for example of 230 V, to a voltage of about 10 V to 25 V. The efficiency of an SELV driver is typically between 70% and 80%. With SELV devices insulation distances of at least 5 mm must be maintained between a primary side and a secondary side with respect to the voltage regulator to protect a user in order to be able to avoid an electric shock to the user caused by leakage currents. In particular, overvoltage pulses of up to 4 KV that originate from a voltage grid should be kept away from the secondary side, so there is no danger to the user even if he or she touches electrically conductive tangible parts, such as for example the heat sink, during the occurrence of the pulse.
LED retrofit lamps can, for example, be designed in such a way that the LED(s) are mounted on a carrier which is screwed to the heat sink and is electrically insulated therefrom. A required length of the leakage path or insulation between potential-carrying or electrically conductive surface regions (contact fields, conductive tracks, etc., for example on copper and/or conductive paste with, for example, silver) and the heat sink is achieved in that, firstly, the potential-carrying surface regions maintain a distance of at least 5 mm from an edge of the carrier and, secondly, an electrically insulating region of at least 5 mm is maintained around the screw connection points. Such a design has a large space requirement, however.